"I'm going to the supermarket. I'll be back later." I don't read any tone in that, out of context. In context you would know the tone of the conversation so it wouldn't come off snappy unless it was meant to be snappy.
With a pause, as far as I can tell. In the 'feminine' to use your analogy. I would suggest comma or dash.
But people don't say that line with a full stop. They pause very briefly before adding, 'I'll be back later', as a kind of continuation of the statement preceding it.
They are two complete sentences, so you say them as two complete sentences. That's all the full stop denotes - the end of a complete idea - not the length of time you take to start the next sentence. Commas don't indicate a pause either, as most English teachers tell us they do.
I don't care if they are two complete sentences. A full stop should not be used in this case. And what does a comma denote if not a pause in speech?
You guys are probably overthinking this. I'm guessing the vast majority of readers would read the sentence about the same whether a period or semicolon were used. The semicolon isn't improper, but like I said above it just looks odd to me in this case.
I love it when people make up words that fill a gap! Dialogually. Not easy to SAY in dialogue, but it makes sense!
It came to me while reading this thread that I don't think I've ever used parentheses—brackets, here in the UK—in dialogue either. Strange. Again, I think it's because you can't 'hear' parentheses when somebody speaks, can you? Nothing grammatically wrong with them, but they just don't seem to be needed in dialogue.
Why? There's no logical reason. It separates full sentences from sentence fragments, or items in a list, or an introductory statement from the rest of the sentence. It has nothing to do with tempo or rhythm of the spoken word.
A comma denotes a pause in reading, or in speaking - it's where the reader (or speaker) takes a breath. Without them, a sentence might be too long. A full stop is used when you move from one thing to a different thing. The "I'll be back later" is still part of the full sentence, "I'm going to the supermarket, I'll be back later." You could also write it as: I'm going to the supermarket and I'll be back later. It's not only used to separate items on a list.
Not sure exactly how that would work. Presumably non-fiction means that any dialogue you 'quote' would be a direct quote of something that was actually said. And if so, would the real speaker have spoken using parentheses? Hmmm....
I apologise, I'm not thinking of just dialogue. I believe they are used to add extra information that might add to a sentence but you don't necessarily need it. I know what I mean (it's a good job someone does) I just have trouble explaining it sometimes.
Oh, I'm not against the usage of parentheses at all. Just their usage in dialogue. I actually use the danged things in narrative more than I should, myself. Just your sentence above is an example of how I don't think it works dialogually. Try saying it out loud, as if we were having this discussion face to face. "I know what I mean (it's a good job someone does) etc...." How would you actually SAY that? I don't hear it being spoken with parentheses. I'd hear it said more like this: "I know what I mean. It's a good job someone does. I just have trouble explaining it sometimes." Or possibly, depending on the sharpness of the break: "I know what I mean—it's a good job someone does. I just have trouble explaining it, sometimes."
Since written dialogue is meant for reading, not necessarily to be read out loud depending on the text, I'd say follow written grammatical rules. The idea of imitating real speech is flawed anyway - you want the illusion, or the feeling of natural speech, but you don't actually want speech as you hear it in real life. Can you imagine how many erms and ahs and likes and wells you'd get, on top of the sheer repetition and small talk!? Commas also do not actually indicate where people pause in real speech - to some extent commas imitate those pauses but there're many places where you'll need commas but there's no obvious pause. The idea of "stick in a comma whenever you pause" is why so many English native speakers can't use commas and end up with poor grammar (as well as the fact that in England it seems they don't honestly teach you English grammar much). Apostrophes can't be heard either - you might as well write "cant" rather than "can't". Punctuation is a tool for the written form of the language - you can't 'hear' any of it! So, along those lines - just use whatever is grammatically correct. There's no rule against the semi-colon so do as you please as long as it's correctly used. I think people are just against the semi because so many people misuse it. (this might go back to the lack of grammar teaching in schools) It's a confusing little mark. And if you're gonna misuse it then it's better not to use it at all when other punctuation marks serve a similar purpose. Semis seem to be outdated or archaic these days, or so that's my impression, and that might well be why people dislike it. It looks technical, too formal, and its lack of usage in most books make it look out of place even when it isn't. All this gives the impression that the semi is pretentious, as if it doesn't belong with the other punctuation marks cus it's somehow 'unnatural', when the feeling of it being unnatural is probably only due to its lack of usage these days, cus people aren't used to seeing it.
In dialogue, I would probably use dashes - because it's extra information - as they make you stop and read it differently.